Patients suffering from low back or leg pain frequently have stenosis of the vertebral and/or neural foramen that constricts their spine-related nerves. It has been shown that applying traction to the spinous processes may alleviate this pain and several devices have been developed that accomplish this. However, many of these devices are either difficult to implant, do not stay in place, or wear away the bone of the spinous process due to poor conformance of the device.
US Published Patent Application No. US20060122620 (“Kim I”) discloses a posterior element distraction system for implantation at a spinal motion segment comprising a superior vertebra, an inferior vertebra, each vertebra comprising a posterior element comprising a spinous process, laminal portions and a set of facet joints, and further comprising an interspinous space between the spinous processes, the system comprising: at least one lateral member for positioning on a side of the spinal motion segment and outside the interspinous space, wherein the at least one lateral member has an unexpanded configuration and an expanded configuration; and first and second transverse members extending transversely from the at least one lateral member, wherein when the system is operatively implanted at a spinal motion segment and the at least one lateral member is in an expanded configuration, the transverse members are caused to contact a portion of either the superior or inferior posterior elements thereby providing distraction between the superior and inferior posterior elements.
US Published Patent Application No. US20060085070 (Kim II) discloses a device for stabilizing at least one spinal motion segment comprising a first vertebra having a first spinous process and a second vertebra having a second spinous process, the device comprising: an undeployed configuration having an axial dimension and a radial dimension substantially transverse to the axial dimension; and a deployed configuration having an axial dimension and a radial dimension substantially transverse to the axial dimension; wherein the radial dimension of the undeployed configuration is less than the radial dimension in the deployed configuration.
US Published Patent Application No. 2005-0203512 (“Hawkins”) discloses an interspinous implant for insertion into an interspinous space between a first and second spinous process, the first spinous process having a first and second side, the implant comprising: a) a first base having a side surface adapted for fixation to a first side of the first spinous process, b) a second base having a side surface adapted for fixation to a second side of the first spinous process, c) a first flexible ligament having a first end connected to the first base and a second end connected to the second base.
U.S. Pat. No. 6,582,433 (Yun) discloses a device and method that immobilizes the vertebral bodies by immobilizing the respective spinous process extending therefrom. The device contains a spacer extending from a body with the spacer adapted to be positioned between adjacent spinous processes so that the spacer may be located close to the spine. A strap connected with the body is designed to engage the spinous processes, such that the device may be adjusted to be positioned about the spinous processes. The device ensures that the spacer remains positioned between adjacent spinous processes. The method to insert the device minimizes destruction to body tissue, thus it is less traumatic to the patient and allows for the patient to recover from the procedure faster than conventional methods.
It is an object of the present invention to provide an interspinous spacer that is easy to implant, remains in place after it is implanted, and whose excellent conformance to the adjacent spinous processes prevents wearing away of the adjacent spinous processes during use.